Amirabadi Received NSF CAREER Award to Improve Renewable Energy Systems

ECE Assistant Professor Mahshid Amirabadi received a $400K NSF CAREER Award for “Universal SiC-Based Power Converters for Renewable Energy Systems.”


Developing Next-Generation Power Converters to Improve Renewable Energy

An energy system is only as reliable as its weakest link, which is why Mahshid Amirabadi, assistant professor of electrical and computer engineering, has received a $400K CAREER Award from the National Science Foundation to improve the weakest links in renewable energy systems.

“Our main goal is to reduce the cost of electricity from renewable energy,” says Amirabadi. “That’s what we have to do to make renewables dominant, which is so important to the environment. Additionally, increasing the reliability of renewable energy systems is crucial to building public trust.”

Power converters are a key component in transferring power from solar panels and wind turbines into the grid. Amirabadi is developing the next-generation power converter—a universal, silicon-carbide based, converter that will be smaller, cheaper and more reliable than those that rely on traditional electrolytic capacitors.

The current converters used in residential solar systems have an average life of 5 to 10 years compared to the 25-year life of solar panels, which means that the overall reliability of the system is cut by more than half. The cost to repair, replace, ship, or install new converters in the system due to this unreliability drives up the overall cost of renewable energy.

Because Amirabadi’s converter will be universal it eliminates the need for a series of cascading converters to handle power conversion between sources, and loads with different forms, voltage amplitudes, and frequencies in a complex power system.

“Therefore, the same converter can be used throughout complex systems, as opposed to our current situation where you need many different kinds of converters,” she says.

Amirabadi’s research builds upon her previous work, including two recent patents: a reliable converter for systems with unequal instantaneous input and output power such as residential solar systems (2019) and a general capacitive-link universal converter that uses soft switching technology to increase efficiency (2020).

She says that several of her proposed converters have been successful in the prototyping process and she is approaching the commercialization stage for those topologies. For now, she hopes to license the inventions through an existing company, but in the future she hopes to launch a startup of her own.

Amirabadi joined Northeastern’s College of Engineering in 2015. Her research interests include design, modeling and control of power converters, power electronics for renewable energy systems, microgrids, variable speed drives and wireless power transfer. She earned her PhD in Electrical Engineering from Texas A&M University.

“I’m really happy with my choice,” she says. “I knew professors Brad Lehman and Ali Abur from conferences, so I was confident that Northeastern’s electrical engineering department would be supportive to junior faculty, which is critical.”

Abstract Source: NSF

Power converters are vital to renewable energy systems and key components in enabling the integration of renewable energy sources into the utility grid. However, high failure rates, large volume and weight, and the high cost of power converters can often restrict the grid penetration of clean energy. Wide-bandgap semiconductor devices, including those made of silicon carbide, are a promising solution for improving power converters, but their merits cannot be fully realized with current converter topologies. The goal of this CAREER plan is to create high power density and ultra-reliable converters by combining wide-bandgap devices with new universal converter topologies that have an ability to eliminate less reliable components commonly used in power converters, such as electrolytic capacitors, as well as bulky components like low frequency transformers. These improvements will contribute to the long-term research goal of the PI, which is to realize ultra-high-performance renewable energy systems. The PI’s long-term educational goals are to increase diversity in engineering and train the next generation of engineers who are aware of the major challenges in the power electronics field and well-prepared for addressing the future energy needs of the United States. There is an obvious need for a more diverse workforce in the energy fields. This project will create an opportunity for several graduate and undergraduate students, including students from underrepresented groups, to learn about wide-bandgap-based power converters and their applications in renewable energy systems. The proposed research is relevant to a wide range of applications, but, for the scope of this work, the PI and her team will focus on renewable energy systems and microgrid applications.

Silicon carbide devices offer significant advantages at the device level, including dramatically higher switching frequency. Despite significant device-level advantages, simply substituting silicon carbide semiconductors for their silicon counterparts will not result in significant improvements to a converter. For instance, in power converters that involve transferring the power from a source to a load with unequal instantaneous values of power, such as single-phase inverters, the size of passive components is not reduced by increasing the switching frequency and use of silicon carbide devices. These converters typically employ large electrolytic capacitors, which have high failure rates. A primary component of this proposal is that it includes a total elimination of low reliability electrolytic capacitors as well as low frequency transformers in all power converters. This will be achieved by creating novel, single-stage multi-port silicon carbide-based converter topologies that accomplish power conversion between any type of source and load, including dc, single-phase ac or multi-phase ac, in one stage, thereby eliminating the need for cascaded converters and decoupling capacitors. These topologies are inspired by isolated dc-dc converters, which can use high frequency transformers instead of low frequency transformers and will be complemented with the use of soft-switching techniques. The input side and output side switches cannot be controlled independently in these converters. The main challenge is the complex control of these converters, especially when the link current/voltage ripple values are large. Therefore, conventional modulation techniques cannot be used. In this project modified modulation techniques will be developed for these converters.

This award reflects NSF’s statutory mission and has been deemed worthy of support through evaluation using the Foundation’s intellectual merit and broader impacts review criteria.

Related Departments:Electrical & Computer Engineering